Hormones play an important role in the bodies of mammals because they act on metabolism and reproduction, as well as coordinate and regulate activities of different parts of the body, organs and tissues. Steroid i hormones possess the capacity to increase weight gain and to reduce the feed conversion ratio, therefore they can be used for anabolic purposes in animal fattening. Taking into account the toxicity of hormones, particularly their cancerogenic and mutagenic properties, the use of this group of compounds for animal fattening purposes has been prohibited in the European Union, but natural hormones are allowed in some countries, for example USA and Australia. However, steroid hormones are also natural constituents of muscle and fatty tissues as well as of livers and kidneys of nontreated animals. Their occurrence is not restricted to . mammals. Steroid hormones have also been determined in fish and poultry; they have been found in other animal-derived food such as milk and eggs. The residues of anabolic hormones in animal tissue as a result of implantation or illegal use can be a hazard for humans. Therefore the monitoring of hormone residues in biological samples of animal origin is mandatory. Several cases exceeding the acceptable limits of 17β-estradiol and testosterone in bovine serum were noted in Poland in the last five years. Moreover, the presence of endogenous 19-nortestosterone in the urine of pigs was observed and no residues of synthetic hormones in tissues of slaughter animals were found.
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This article is a review of recently published papers dealing with the possible participation of environmental hormonally active compounds (natural and synthetic) in the ethiology of reproductive and other health disorders in animals and man. For some "old" synthetic chemicals (DDT, PCBs, dioxins, diethylstilbestrol, bisphenol A, atrazine and tributyltin) there is a link to the impact on wild animals. It has been hypothesized that in humans these compounds may be responsible for the increased incidence of breast and testicular cancer as well as for reproductive disorders. They generally occur at nontoxic concentrations, but exposure to their mixtures seems to be a major medical challenge. The food and drinking water are the main routes of exposure. During last decades much concern is focused on new groups of chemicals such as brominated flame retardants, phthalates, perfluorinated chemicals, parabens and veterinary drugs (anabolics).
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In this paper the pharmacological properties of azalides, an improved group of macrolide antibiotics, have been reviewed. Worldwide interest in macrolide antibiotics has led to the development of several semi-synthetic derivatives of 14-membered erythromycin, such as 15-membered azithromycin and tulathromycin, with an additional nitrogen atom in the lacton ring. The newer macrolides, called azalides, have broader antibacterial activity against Gram-positive and Gram-negative pathogens as well as atypical pathogens of the respiratory system. They are characterized by better pharmacokinetic parameters, reduced adverse reactions and an improved drug-interaction profile compared with erythromycin. The application of these groups of antibiotics has some advantages over erythromycin, including longer half-lives and higher tissue concentrations, especially at the site of infection, which makes it possible to administer them once a day in the treatment of respiratory tract infections, in contrast to more frequent dosage required for erythromycin. Azalides are more acid-stable and therefore demonstrate greater oral bioavailability. In addition, these antibiotics have immunomodulatory and anti-inflammatory properties, which can be useful in the treatment of chronic disorders. The pharmacokinetic/ pharmacodynamic relations, which are important in predicting clinical efficacy of antibiotics, are also reviewed. To ensure food safety, the European Commission had set Maximum Residue Limits (MRLs) for erythromycin, as well as for tulathromycin. However, azythromycin has not been certified for use in food producing animals, and therefore no MRLs have been established for this azalide.
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The paper presents the results of monitoring of PCB residues in food of animal origin for the 12 year period of 1997-2008. The residue control plan included analysis of PCB congeners IUPAC No 28, 52,101,118,138,153 and 180 in a variety of food samples. The residue control program exists in accordance with Council Directive 96/23/EC and legislation of the Ministry of Agriculture and Rural Development. The residue examinations are performed by the National Veterinary Research Institute in Pulawy (National Reference Laboratory) and Veterinary Inspection Laboratories (ZHW) located in Bialystok, Gdańsk, Katowice, Poznań, Warsaw and Wroclaw. The determinations of PCB congeners were conducted using capillary gas chromatography with electron capture detection. Over the period of 12 years residues of PCB congeners were determined in 19 767 samples. The examinations involved the adipose tissue of pigs, cattle, sheep, horses, game (wild boar, roe deer, and deer), chickens, geese, turkeys, ducks and rabbits, farmed fish muscles, cow milk, eggs, honey and import food (mainly marine fish). More than 35% of the samples were found to contain low concentrations of PCBs. In swine and poultry tissues the lowest frequency of PCB residues has been noted. The following highly chlorinated congeners were most frequently detected: PCB 153, PCB 138 and PCB 180. The mean concentrations of indicator PCB congeners were higher in fish and game animals then in other animal species. Generally the levels of PCB congeners were several times lower in comparison to the permitted maximum residue limits in other countries. The regular testing within the national residue control program indicates that Polish food of animal origin contains low levels of these contaminants and is safe for consumers.
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Thyreostats are thioamid antithyroid drugs. The activity of these compounds consists in inhibiting the synthesis of thyroid hormones: triiodothyronine (T3) and thyroxine (T4), which favors the processes of fattening animals. The weight gain of animals is mainly due to water retention in their tissues and gastrointestinal tract. Because of the cancerogenic and teratogenic properties of thyreostatic drugs, their use for animal fattening has been banned in Europe since 1981. Control studies conducted in Poland show that thyreostats are not used in farm animals. Several cases of endogenous thiouracil content in the urine of cattle and pigs have been reported over recent years. This article presents the properties of thyreostatic compounds, discusses a possible cause of endogenous thiouracil occurrence, and provides an overview of methods used in the analysis of thyreostatic residues.
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